Recording and including resonant vibratory aspects



June 1952 D. R. YARNALL ET AL 2,600,822

RECORDING AND INCLUDING RESONANT VIBRATORY ASPECTS Fi led March 27, 19479 Sheets-Sheet 1 ID masWJ IM:

June 1952 D. R. YARNALL ET AL 2,600,822

RECORDING AND INCLUDING RESONANT VIBRATORY ASPECTS Filed March 27, 19479 Sheets-Sheet 2 .IIIIIITIJI June 17, 1952 D. R. YARNALL ETAL RECORDINGAND INCLUDING RESONANT VIBRATORY ASPECTS Filed March 27, 1947 9Sheets-Sheet 5 0 I Wm orflfllllllflll lllnllllllnnllllllvlllllllIIIIIIIIIIIIIIIIIIIII' III I J1me 1952 D. R. YARNALL ET AL2,500,822

RECORDING AND INCLUDING RESONANT VIBRATORY ASPECTS Filed March 27, 19479 Sheets-Sheet 4 ORNEYSV June 1952 D. R. YARNALL ET AL 2,600,822

RECORDING AND INCLUDING RESONANT VIBRATORY ASPECTS Filed March 27, 19479 Sheets-Sheet 5 1775a 22% p l I June 17, 1952 YARNALL ET AL 2,600,822

G RESONANT VIBRATORY ASPECTS RECORDING AND INCLUDIN Filed March 27, 19479 Sheets-Sheet 6 June 17, 1952 D. R. YARNALL ET AL RECORDING ANDINCLUDING REISONANT VIBRATORY ASPECTS 9 Sheets-Sheet 7 Filed March 27,1947 INVENTORS /w al June 1952 D. R. YARNALL ET AL RECORDING ANDINCLUDING RESONANT VIBRATORY ASPECTS 9 Sheets-Sheet 8 Filed March 27,1947 ATTORNEYS.

June 17, 1952 D. R. YARNALL ET AL RECORDING AND INCLUDING RESONANTVIBRATORY ASPECTS Filed March 2'7, 194'? 9 Sheets-Sheet 9 2'. ATTORNEYSPatented June 17, 1952 anoonn no AND INCLUDING RESONANT vrnnA'ronYASPECTS David Robert Yarnali; Philadelphia, and James W; Williams, 3rd,;Ambler,- Pa assignors ,to Yarnall-Waringl Company, Philadelphia, Pa., acorporation of Pennsylvania Application March 27, 1941', SerialNo.v 737578 1 Our invention relates to recorders primarily in-,

tended for indicating and. recordingwater level in connection with steamboilers and the like, but

suitable also forindicating and recording datav of numerous other types.

A purpose of our invention is to reduce friction incident to-recordingand primary indication without increasingthe complexity of the.

recorder.

A further purpose is to impose vibration suitably by electromagneticmechanism axially upon a primary-indicator shaft to reduce the bearingfriction of the shaft.

A furtherpurpose-is to support amarker on the end ofa pivoted arm-bymeans having aparticular natural frequencyand to impose on-the armvibration at that natural frequency and preferably applied axially ofthe arm.

A, further purpose is to employ a marker supporting arm which isresilient adjacent the pivot, relatively stiff between the pivot and theouterend and resilient at the end supporting the marker, to'vibrate thearm preferably byalterhating current electromagnetic impulses from anelectromagnetappliedtothe resilient portion at the axisand preferably totune the resilient portion, at the end supportingthe marker, tothevibration.

A further purpose is to mountthe "marker'on a comparatively rigid arm-bya: V- spring clip, one of the branches of the V being securedto thecomparativelyrigid portion ofthe arm and the other to the marker and toadjust the length of the free branch-carrying the marker to a naturalfrequency which correspondsto the vibration applied to the arm.

A further purpose is to supporta markerfrom a primary indicator shaft-byan arm having an axially resilient connection with the primaryelement, obtainable, for example, by areversebend or offset in the armnormal to the axis of rotation, a stir? section between the resilientconnection and the end and a resilient section on the end a.d.

joining the marker, tomount an armature at the axis adjacent to thestiff section of the -arm and n e pp s te ds fz he esi ien onn ctio tthe p mar di ator shaftandz o r t 'the armature preferably byalternatingcurrent else-.-

tromagnet means 'actingeither from outside or- A further purpose is toemploy a circular chart rotating about an axis and having a portioncurves to cooperate with the path of am preferably moving about an axistransven the axis of the chart.

further purpose is to curve the radially outer upper portion ofacircular ChQI't-QIld tQ mQY Q;

the marker about an axis transverse to the chart along a centralvertical radial path of the charts;

A further purpose, is to place the primary indicator shaft behind thechart, and to car ythereverse end around the, chart, the remainder ofthe ma1-kerarm being in front of the chart A. further purposeis todamothe vibration'by relieving the chart plate behindithe chart and;vibrating against the unsupported paper.

A further purpose is to maintain the, chart;

paper resilient under the vibration.

A. further purpose is to damp the. vibration .by.

maintaining themarker slightly-out of resonance with the vibrationsource. 1

A. further purpose isto vibrate the. marker without breaking the inkstream or filmbetwe'enthe mar-her and the chart paper.

Further purposes appear in the specification in the claims.

In the drawing wehave chosen to illustratea,

few only-c1"- thenumerous embodiments in wl'iich our invention may p er, t e ferns shore-b ing chosen-from the standp 'nts of conv'enl nceFigure 2 i a i em e evat onwhh herewfliii chart and theindicator windowr x naway- FigureS is asectionon .the line 3-.- 3. of,Figure 2. Figure i.is a detail v perspective, shovvine;.the

marker arm, vibrator andindicating arrn.

Figure .5 is. a detail elevation of theendof the marker arm showingthemarker.

igure 6 is a cent al. t ca s stion h ough.

the primary indicator.

i re 7 s sec ion .O Figur 60 M 1 l ne.

5-7 to reduced scale.

Figure 8 is a detail perspective of the hors e ma n nd uppo tior theprimary ing cator.

Figure 9 is a detail side elevatio n of ,a variant primary indicatorspiral.

Fi u s a. agrammat -;e1e PEI-1.113%

in sectio s o n a o 'der g c dins- 1 the invention applied as a liquidlevel recorderma,

high pressure boiler, with the recorder located in position to be readfrom the floor.

Figure 11 is a diagrammatic elevation, partly in section, showing thinvention applied to flow meter measurement of a liquid passing throughan orifice.

Figure 12 is a fragmentary elevation, partly in section, showing theinvention applied to recording flow through a Weir notch.

Figure 12 is a view of the weir notch of Figure 12 in sectionalelevation.

Figures 13 to 17 inclusive illustrate a modification in the recorder ofthe present invention.

Figure 13 is a front elevation of the modified recorder.

Figure 14 is an end elevation of Figure 13.

Figure 15 is a fragmentary detail side elevation of the marker arm andrelated structure.

Figure 16 is a top plan view of the structure of Figure 15.

Figure 17 is a section on the line l1--|1 of Figure 15.

Figures 18 to illustrate a variation in the marker and recording arm.

Figure 18 is a fragmentary enlarged side elevation corresponding inposition to Figure 1'5.

Figure 19 is a fragmentary front elevation of Figure 18.

Figure 20 is a fragmentary end elevation of Figure 19.

Figures 21, 22, 24 and 25 are fragmentary side elevations correspondingin position to Figure 15, and showing various alternate forms of axiallyresilient connections.

Figure 23 is a fragmentary front elevation of Figure 24.

Figure 26 is a reduced front elevation of a variation in the recorder inrespect to the position of the primary indicator axis, the relief of thechart plate and the illumination.

Figures 27 and 28 are enlarged longitudinal sections through the inkdischarge tube transverse to the paper, at the extremes of a dampedvibration cycle.

In the drawings like numerals refer to like parts.

Describing in illustration but not in limitation and referring to thedrawings:

Where a primary indicator shaft is rotating in response to a quantity tobe indicated, such as the level of liquid in a boiler, the flow throughan orifice or over a weir, or any other quantity being measured andrecorded, recording presents a diflicult problem unless amplification ofthe energy of the primary indicator is to be used.

While such amplification is often highly satisfactory and quiteaccurate, it usually adds considerably to the cost of the mechanism, andoften increases the maintenance.

By the present invention it is possible to record the indication of aprimary indicator without imposing any substantial frictional or otherburden on the primary indicator, and often with actual reduction in thefriction. In general we provide a simple arm mounting for a marker suchas a pen on the primary indicator shaft, designing the arm so that itwill transmit very effective vibration to the marker and thereby greatlyand continuously reduce the friction between the marker and the paper orother material of the chart.

Considering first the recording mechanism of Figures 1 to 5 inclusive,these figures illustrate a case 25 having a door 26 provided with atransparent window 21 for viewing a recorder 28. At

'4 the opposite end of the case an indicator 29 is provided, suitablyconnected by nipples 30, 3| to a source of pressure differential whichdetermines the indication as later explained.

The indicator 29 has a window 34 through which may be viewed anindicator pointer 35 mounted at 36 on a primary indicator shaft 31 andsuitably counterweighted at 33. The primary indicator shaft 31 turns insuitable bearings 39 on a primary indicator housing 48, described indetail below. Suitably mounted as by screw 41 on the end of the primaryindicator shaft 31, a, marker arm 44 is provided, preferably made ofnonmagnetic material. The marker arm has a resilient connection such asa reverse bend 45 which passes back across the axis of the primaryindicator shaft 31 at 45. It is then conveniently bent again at rightangles at 41 in this form, and at its outer end supports e. marker 48,which may be of pencil or crayon type, but will preferably be a pen ofthe 003111105 type used in recording, in which case there will be an inkreservoir 49, an ink discharge tube and a pen point 5! as best seen inFigure 5.

The marker arm 44 in the preferred form essentially comprises threeportions. The axially resilient portion 54 illustrated in Figure 4 inthe form of a reverse bend may consist of a spring preferably ofberyllium copper, Phosphor bronze or other nonmagnetic spring material,sufficiently resilient to form a hinge portion and permit the marker armto move under the action of the magnetic force. The portion 55, whichmay be welded or otherwise attached to the resilient hinge portion 54,is preferably of thin walled stainless steel tubing, aluminum or otherlight metal, and is, as compared to the axially resilient portion 54,quite rigid and unyielding under the forces encountered. The support 58from the arm for holding the marker is a spring of beryllium copper orother suitable spring material. As best seen in Figure 5, the spring 56is suitably of V shape, having one arm 51 secured to the portion 55 asby welding or brazing, and the other arm 53 holding the marker insuitably resilient clips 59 preferably integral with the material of thespring 55.

The spring 56 is selected to have, with the particular marker, a naturalfrequency or natural period of vibration generally corresponding withthe alternating current frequency which will be used for purposes ofvibration, and the marker is suitably positioned along the arm 58 totune the mechanism to any suitable harmonic of this frequency.

Thus if the alternating current is at 60 cycles, the spring 56 shouldhave a natural frequency suitably close to 60 cycles or some harmonic(multiple) thereof. The natural frequency of the spring can becontrolled by varying its length and by the position of the marker.These final relations are best determined experimentally. The stop 60 isprovided to register the marker in its correctly determined position.

Suitably supported from the housing 46 by bolts 5|, a bracket 54 isprovided, having convenient resilient mounting clips 65. In the clips anelectromagnet 66 is mounted, having a core 61 and a coil 68, withterminals 69, 10 connected to an alternating current source 1| suitablyat 60 cycles and volts. The electromagnet is aligned as shown on theaxis of the primary indicator shaft facing the arm 34.

To the arm 44 an armature 14 suitably of soft iron is welded, brazed orotherwise attached. The armature 14 issuitably of buttoniormation and isdisposed centrally with respect to the axis of the primary indicatorshaft 37 when the marker is in marking position.

A chart plate 15 is employed, conveniently having a straight portion H3which includes the center of the chart plate at 1?, and a curved portion18 which follows the curvature of the path of the marker arm about theaxis of the primar indicator shaft 3': from some point 1%! far out onthe radial path to some point 80 close to the center of the chart plate.Thus it will be seen that as the marker arm moves the marker overv thecurved path, best seen in Figure 3, from the point 79 to the point 88,the marker conforms to the curvature of the chart plate.

Near the center of the chart plate is located a chart rotating motor 8!of well known type, interconnected to the chart by a speed reductiondrive 84, the drive carrying on the outside of the chart plate a lockinghub 85 for engaging a chart 86 and rotating the same. The motor ismounted on bracket 64. As best seen in Figure 1, the chart 86 iscircular but conforms to the shape of the chart plate, resting flatagainst the chart plate at the ilat portion it (Figure 3) and curvingover the curvature of the chart plate as the chart rotates over thecurved portion 18. To hold the chart against the front or" the chartplate at the curved portion, a curved finger 31 is provided, extendingdown from the top slightly in front of the chart plate and out of linewith the axis of the chart.

The chart plates may be formed from sheet metal along conventional linesor they may be 1:.

made of transparent or translucent material such as acrylic orurea-formaldehyde plastic. In the latter case, the chart may beilluminated by an electric lamp from behind and the record and chartmarkings will stand out in relief. Movement of the marker arm causes themarker to move radially with respect to the chart, preferably along thecentral vertical radius in vertical line with the axis of the chart, asbest seen in Figure 2. In this way the device is entirely symmetrical.It will be evident as best seen in Figure 3 that the indicator 35 andthe marker arm need not have either the same radii or the same angularposition at any moment.

A spring clip 88 is mounted on the case Figure 3, to retain the markerarm in an inactive position while changing charts, or to provideclearance for the chart plates when it is necessary to pull the chartplate forward for the purpose of effecting adjustment to the instrument.

The device of the present invention imposes very little extra workrequirement on the primary indicator.

In operation, once the chart is properly mounted with its upper portionconforming to the curvature of the chart plate, and with the chartdriving motor turning the chart, the primary indicator can be throwninto operation by any suitable mechanism such as that later described.This will bring the marker arm to the, proper angular position formarking, but will not bring the marker into contact with the chart dueto the fact that the spring at 54 holds the armature M slightly awayfrom the electro magnet, and holds the marker slightly raised from thechart. As soon as the connection to a source of alternating current ismade, as by throwing a switch 89, the armature i4 is drawn in ol'osetothe electromagnet, bringing the arm.

into a position in which the marker: touches the paper of the chart.Throughout the operation the marker remains practically against thechart, but vibrates back and forth toward and away from the chartthrough a very short distance, suitably of the order of 3 of an inch. Atthe same time the armature 14 moves back and forth very slightly towardand away fromthe electromagnet, but always very close thereto.

Thespring portion 54 functions asa-hinge, allowing the rigid portion 55of the arm to transmit vibration to the spring clip portion 56, thustending to vibrate the marker. Dueto the fact that the marker is mountedon the clip in a position such that the natural frequen'cy'of themarkenandclip corresponds to the frequency ofthe alternating currentused invibration, the marker will vibrate with-notice able amplitudewhile the arm 55 appears to the eye to be entirely stationary.

When it is-indicated that the natural frequency or tuning ofthe markerand clip combination corresponds to that of the alternating frequency,

it is not meant necessarily that it is identicalwith the 60 cycle orother frequency used, but it is intended that it will either approximatethat of the frequency used, or of a harmonic thereof, as well known inthe art; natural frequency might be a multiple of the 60 cyolesif 60cycle alternating current be em In cases slight variance with theapplied frequency of vibration. This effects a decrease in amplitude Iof the marker movementto that desired.

It will be evident that direct connection between the primaryindicatorand the marker has been provided, since the marker arm is directlymounted on the primary indicator'shaft and directly follows the motionof that shaft. A single simple moving element thus provides both theindicating and recording function. While the loadon the primaryindicator bearings is increased somewhat, the same contact betweenbearing surfaces is used as where the indicator alone is employed, thusminimizing additional friction. Since the indicating and recording armsare on the same shaft, it is very simple to find the desired relationbetween the indicating scale and the recording scale to regulate the,distance of the marker from the center of frictionagainst the paper, andalso aids in ink- I'low. At the same time 1 the vibratoryactioncompensates for errors in the curvature or surface of the chartplate or of the paper of the chart, and for might otherwise cause therecording arm to jam or catch.

The constant vibration introduced by the electro-magnet continuouslyproduces interruptions bothincpen-paper contact and also in bearing,contacts on the primaryindicator shaft, thusim- H Thus the slightmisalignments of the indicating and recording mountings, which.

7 proving bearing lubrication and, on actual test, reducing bearingfriction.

Due to the fact that the contact between the pen and the paper isinterrupted at a suitably rapid rate, there is no marker friction duringthe noncontact interval, and the indicating and recording elements canrespond with the same degree of accuracy of indication as would occur ifthe marker did not contact the paper. The effect of the intermittentvibratory contact with the paper is merely to damp the response but notto affect the accuracy of the final position reached.

The vibration extending axially to the bearings of the primary indicatortends to lower the average bearing friction to such an extent that basedupon observations it is found that there is higher sensitivity with therecorder unit attached and operated than with the indicator alone. Theexplanation appears to be that the vibration temporarily reduces bearingpressure at a given point and alternatively improves bearing lubricationwith resilient freedom of motion.

The fact that the electromagnet pulsations on the primary indicator areaxial thus prevents the development of components of force transverse tothe axis of rotation. The pulsations do not in any way influence theaccuracy of indication. The amplitude and frequency of the vibrationsimply controls the amplitude and frequency of the vibration of theprimary indicator shaft in the direction of its axis, and simplycontrols the motion of the marker toward and away from the paper (in adirection which is unimportant from the standpoint of measurement of thequantity which is recorded).

The flux of the electromagnet acts symmetrically upon the armature 74.

Since the device is designed so that in case of current break the spring54 lifts the marker away from the paper, the mechanism remains free frommarker friction in case of interruption of the current. Therefore underthese conditions the only load imposed by the recorder would be theweight of the marker arm and marker.

The circular chart as shown records along the vertical center line ofthe upper portion, with the lowest recorded point on the chart locatedslightly above the center of rotation of the chart. This permits thechart and chart plate to be of the conventional vertical form except inthe upper curved portion where the usual circular chart conforms to thecurvature. The conven tional chart drive can be used, since the chartaxis is located below the curvature.

This chart construction provides more convenient visibility of the mostrecently recorded data on the chart, since the most recently re cordeddata is at the top and readily visible to a person looking in throughthe window. In cases where the non-transparent type of chart plate isused, the greater projected area of the upper part of the chart providesbetter illumination from an electric lamp or the like concealed in theupper forward part of the instrument housing.

It will be evident that in the form just described the electromagnetoperates from outside the reverse bend of the marker arm, but, as laterdescribed, an electromagnet can equally well operate in the oppositedirection, in either case being on or substantially on the axis of theprimary indicator.

While the recorder of the present invention is of general utility, it isparticularly useful with a primary indicator of liquid level, flow orthe like of the type contained in Walter J. Kinderman U. S. applicationsSerial No. 517,242, filed January 6, 1944, now Patent No. 2,509,644,dated 30, 1950, for Difierential Pressure Gage, and Serial No. 713,035,filed November 29, 1946, for .Jvieter. In these devices angular motionfrom a primary indicator shaft is transmitted without substantialfrictional loss from a closed space in response to pressure differentialor the like within the space.

'The housing ":0 of the indicator as best seen in Figures 6 and '7comprises a body and a cover 9| united by bolts 94 and sealed by annularpacking 95 on opposite sides of a diaphragm support apertured at 91. Thediaphragm support for convenience is recessed at 98 on the side towardthe body 99 in order to permit a well, later to be described, to fitinto the recess. The housing is mounted in any suitable position, suchas vertical, by a bolt entering threaded opening On the side toward thecover, the diaphragm support is recessed at I29 to permit collapse intothis space of an annular transversely free flexible diaphragm portionIQI of a diaphragm I04. The diaphragm is held at its outer edge by thepacking 95 which protects against leakage between the support and thecover. At the center the diaphragm is stiffened by diaphragm plates I05which are united by threaded members I08, I01, recessed at I98 toreceive a thrust pin I09 engaging in a conical socket III! and extendingthrough an opening I i I in the threaded member The pin I09 carries acollar I I4 to prevent accidental removal of its end from the space I88.

The diaphragm I54 subjected to differential pressures on opposite sidesthrough nipples 30, 3 I. The pressure upon the outer face at 3| is astandard pressure in the liquid level measurement form, which should beequal to or greater than the pressure obtained due to the highest levelof liquid indicated.

At the opposite end, the thrust pin I09 engages within a cavity I15 of athimble IIB which is mounted as by peening at II! on a leaf spring H8.The spring provides a convenient support for a horseshoe magnet H9. Thespring supplies ehective retardation for the movement of the magnet. Thehorseshoe magnet H9 is conveniently mounted on the spring by extending aplate I20 over the magnet and thimble and bolting through the plate,magnet and spring at I2l. The thimble may conveniently be peened over atI24 to unite to the plate.

The motion of the magnet is transmitted to the primary indicator shaft31 through a pressure Wall or well I25 of suitably nonmagnetic material,which surrounds a magnetically susceptible rotatable armature I26 ofspiral formation which is external of the housing 4!] in the sense thatit is not subjected to the pressure of the housing. The magnetictransmission is based upon the change of reluctance of the magnetic pathwith movement of the magnet at right angles to its flux and along theaxis of the armature, accompanied by rotary reaction of the armature tothe magnet movement to reestablish the reluctance of the magneticcircuit at a balanced position.

The magnet I I 9 is preferably a permanent magnet of highly magneticalley having curved poles I21, I28, which effectively surrounds the wellI25, with suitable clearance to permit movement longitudinally of thewell. A suitable magnetic alloy is Alnic (24 to 30% nickel, 9 to 13%aluminum,

balance iron) crAInico (%..nicke1, %a1uminum, 5% cobalt, balance iron)as well knownin the art.

The well is threaded at I29 into the housin and internally'threaded atI30 to receive-athreaded p us I3 I which holds a jewelled'bearing I34for theprimary indicator shaft 31. At the opposite end of the wellianinsert I35 holds an opposite jewelled bearing I36 for the opposite endof the armature I26.

{In Figure 6 the armature I26 is of uniform spiral pitch throughout.However in many cases the variation in pressurezand the like which comesto the housing may not uniformly follow the quantity being indicatedsuchas liquid level or 'fiow, but may be a nonuniform function thereof.

as for -example where the device depends upon the law of a weir. In suchcases the pitch of the :spiralmay be made nonuniformincreasing ordecreasing in either direction or agreeing to any predetermined law asshown at I26 inFigure 9. Thiswill permit use ofa uniform indicatorscale, and making of uniform recordings on a chart,

notwithstanding that the pressure variation is nonuniform.

The armature may preferably be made of soft iron or low carbon steel,such as Swedish iron or so-called core iron. Silicon bronze has beenfoundto be satisfactory as a nonmagnetic material for the well I25. Ithas been found that the relation of the spiral pitch to the magnetthickness should be relatively high. A4 to irelationgives good resultsanda 3 to 1 relation is acceptable.

Provision is made for adjustment of the fulcrum of the spring I I8.Movement of the fulcrum edge normal to the plane of the spring controlsthe zero setting, while movement of the fulcrum edge along the surfaceof the spring-parallel to the spring length changes the unsupportedspring length andqtherefore changes deflection characteristics. This isequivalent to calibrationfor range of liquid level travel or range for agiven indication.

The spring is desirably supported at its rear end betweena transverseblock I31 and its cap I38, both held togetherby bolts I39. If the supporting spring were of the same thickness and width throughout itslength, the possible adjustment in range of movementdue to fulcrum ad-53 justment would be relatively small. To increase the effect. ofchange in fulcrum, thespring can be varied in thickness or, as :is moreconvenient in production, can be variedin width where it bent. isslotted at,I40 adjacent thesupporting end MI, and thewalls adjacent thebifurcation are tapered oppositely at I44. The outer walls are taperedinwarcllyand upwardly toward the-upper endat I45.

Although. the spring is at all times supported 7 by the block and thecap, the effective .lengthof thespring .is determined .by anadjustablefulcrum in the form of a bar I46 havingalrnife edge I41 extending acrossthe spring. The bar I46 ismovable transversely of the length of knifeedge. The bar I46 is slottedtransversely at I48 from the back soas topermit it to be slid fromtherightin Figure 6 upona barrel MS of a spoolI50 having flanges I5I. ,The spool is rigid.

with a screw I54 threaded into the housing, 4% and into the block I31.The screw is accessible I for turning through an opening I55 closed byaclosure bolt I56. Adisc I51 on screw I58mounted .in the housingbehindthe bar I46,,mov,es the, ,bar

The spring ,is accordingly made wide and .T

closure bolt I .6 B.

10 to thelctt. or. r ht i i ur and o r ondi lymoves thefulcrum. Accessto the screw, I58 is provided through an opening I59 closed by a Sincethe setting of the zero pointcf the indicator is dependent upontheposition of themagnet to the right or left in Figurefi,

the zero point can be adjusted by advancing or retracting the disc I51.A set screw I61 prevents lowering of the bar I46 beyond the limit of.ad- .justment.

In operation, the device of Figures 6 to 91$ controlled ,by motionof thediaphragm under differentialpressure, which causes .the pinI 99 to movethe. horsesho ma e I I9 eea n th e rd ti ,c thesprins M vem n o th horsshoemaenet su roundi he W ca ses th sidesrof a diaphragm I04 as shown invFfigure 6.

ln'this ,form the pipe connectionv I15 carrying varying pressurecommunicates with the nipple 30 at theleft hand side of Figures land 6.The pipe I14 communicates with .the oppositeside of the diaphragm inFigure 6. As v he variant water level communicating with the lowerpressurepot I1I drops, th e pressure difference with respect to theconstant level in pressure pot I10 increases and th magnet is shiftedalong the well toward theindicato that s, u w lone h rmatur vso astogive progressively'lower indication for lower variant,water;level.

In Figure 10 the two pipes I14, I15 are closed or opened by valves I16.

, In Figure 11 the fiowpipe .I11and I13 isinteruptedto provide. fla edte m na s H9. we. bo ted to e h about n o fice pl t It I. e flow pi topipe thepressurefrom opposite sides of the orifice to theindicator andrecorder. It willbe re o ni d. tha n th fo mo i ure t e p p r p esents.a tandard ma m pres ureni e maintained at maximum pressure bycondensation, and containing a constant head reliably .ab v the leve .oth W te i th st a d um howev bot of ,th 'pre sures i th fl w-pipe rm ,oF gur l ;fluctu te a d th i rmedia ran mi sio o h ndi o o t in rpret t oor example a' b io o th n icato must ,take into account the law ofvariation betwe n :Lth twov pr u e t di e r ssur values and differentquantitiesof fiow. In Figure lith pipe I I8 a e conne te t espe t v nlesfifl. 3. o the i i to en re orde .In. F g r .1 t i ent o i a pli to rc ing fluid floworindica nsm ely t ate o o l qui throu h a e m te afor oweir being shown. at 2.36 in plate hilofligurelZ.

water in open feed water heater Iiia passes through a valve I59controlled by, any storage space float, not shown, through .aroclrershaft iiiiiand rocker arm IQI as to control the Supply of water from theheater entering the weir and affecting water level I34. Steampressure-in the heater and neteinare.equalized by pipe I95.

The illustration in Figure 12 is modelled generally after theillustration in Figure 1 of Yarnall U. S. Patent No. 1,143,344, issuedJune 15, 1915, and from which patent other mechanism normally associatedwith that shown in Figure 12 may be seen, and its operation as well asthat of the parts shown in Figure 12 may be checked and furtherexplained. Other Yarnall patents show ing structure to which thisinvention may be applied are 1,159,147 to 1,159,150; 1,178,463;1,200,684; 1,307,609.

In connection with the type structure shown in these Yarnall patents,pressure pots I and III of the character shown in Figure 10 are used tocarry vapor space pressure as a standard, and variant pressure of thewater which is above the weir, through pipes I14, I to the nipples and3!.

The differences in water level yield corresponding differences inpressure in pipe I15 but do not give a true indication of the quantityor rate of flow, since interpretation of water level into rate orquantity of flow involves application of the 5 power or other law of theweir according to the shape of the Weir selected. An armature of thetype shown in Figure 9 may be used to obtain direct readings andrecordings from a weir having a nonuniform function in terms of flow.

The invention may also be applied to a recorder having a flat chart, andto one in which the elec tromagnet is within the return bend of themarker arm, rather than outside the return bend as in the form ofFigures 1 to 5 inclusive. Figures 13 to 17 inclusive illustrate a deviceof this directly front and back in the case and terminating in atightening hub 85 on the end of the chart rotating shaft driven bymechanism identical with that described in reference particularly toFigure 3.

The indicator, identical with that already described, is placed at rightangles to the position in Figures 1 to 5. As seen in Figures 13 and 15,the primary indicator shaft 31 is parallel to the axis of rotation ofthe chart, the primary indicator shaft being preferably located slightlyabove and to one side of the chart so that the marker arm 44' willdescribe on the chart a curved path I98, as well known.

As best seen in Figures 15 and 16, the chart plate 15' extends into thespace in prolongation of the primary indicator shaft 31 and suitablyconsists of some nonmagnetic and preferably transparent material such asacrylic or ureaformaldehyde plastic. The marker arm 44 has a slightlydifferent form of reverse bend 45, resilient as previously described,and has its armature 14 facing toward the inside of the reverse bend asseen in Figure 15, rather than facing outwardly as in Figure 4. Theportion 54' may be a beryllium copper spring. The stiff portion of themarker arm may be substantially identical with that of Figures 1 to 5inclusive except that the bend 41 is not needed and the portion 55 canbe straight as shown.

The marker (pen) 48 may be identical with that previously described, butin this form a straight spring clip 56 is used, properly tuned to thedesired frequency and for a given position of the marker along the clip,rather than a V clip as in the form previously described. The clip 12may be attached to or integral with the stiff portion 55.

In the simple form shown on Figures 18, 19 and 20, the tube member 55 isflattened at the end to form the spring clip member 56 and the penholder 59. The required degree of resonance with the imposed vibrationis obtained by controlling the length of the flattened section.

The electromagnet as here used is placed inside the return bend on theaxis of the primary indi cator which presses through the armature 14,rather than outside the return bend as in the other form. In mountingthe electromagnet it is convenient to support it by a bracket B-Vfromthe chart plate 15. Also in this form the electromagnet is provided notonly with a coil 68' and iron core 61' running through the center of thecoil, but also with an iron magnetic circuit element in contact with thecore at the back at 61 and providing gaps at the front at 61 whose airgap will be reduced by attraction of the armature 14 when alternatingcurrent of the selected frequency is passed through the electromagnet.The return flux path 61 is suitably provided with pole pieces 61 at itsouter end, as best seen in Figure 17, Or by means of any other suitablereturn flux shell or cup about the coil as well known.

It will be evident that the form of Figures 1 to 5 inclusive or the formof Figures 13 to 17 inclusive may be used interchangeably with anysuitable primary indicator, such as that set forth in Figures 6 to 9inclusive, and in any suitable indicator arrangement, as, for example,one of those illustrated in Figures 10, 11 and 12. It will be evidentalso that the primary indicator and the arrangement of connections tothe source of the indication are subject to wide variation to suit theparticular requirements of any individual installation.

In an alternate arrangement as shown in Figures 18 to 20 inclusive, therecording arm and the clip at the end supporting the marker are madeintegral from thin walled tubing, for exam ple of stainless steel. Therelatively rigid portion 55 is tubular in section, and the resilient end55 is formed by flattening the tube, and bending at 59 to encircle andgrip the marker 48, whose reservoir in this case extends transversely tothe position of Figure 15.

The axially resilient connection between the primary indicator and therecorder arm may take various forms as shown in Figures 21 to 25inclusive, other than the reverse bends shown. For example, in Figure 21we illustrate a variant having an axially resilient connection in theform of a spring loop I91 in a suitable plane, here a plane through theaxis, and in this case preferably symmetrical with respect to the axis.The particular loop is circular, but this feature is unimportant.Torsional stresses in the loop may somewhat modify the vibration. InFigure 22 the axially resilient connection takes the form of a doublereturn bend spring I98 having bend sections I99 and 200. Thisconstruction gives a. high degree of axial resilience and is consistentwith a high degree of lateral stiffness and resistance to deformation inother directions.

The simple return bend may also be split longitudinally to form twinreturn bends MI and 204 symmetrically offset from the center line of thearm as shown in Figures 23 and 24. This form permits high axialresilience, with great resistance to deformation in other directions.Figure 25 shows a rigid return bend 205 having,

- corder.

atjtheend of its vibration cycle, on the '"or stream 225.

near ,iitsponnection to the rigid portion of :the arm, pins, 205 and20'! passing throughholes 208-and 209inthe arm, and limiting. helical.

compression springs ZiOandlil .on one side of thearm and similar springs2H; and M5. onthe otherside. Nuts 2l6 are threaded on the ends ofthepins to adjust the tension :of the springs -and control the axialfreedom of the recordin --arm.

.shown, the springs may be of any other type.

.Whilc compression springs have been In Figure 26 a variation isillustrated in the form of Figures 13 and 14. As shown, thev axi ofrotation'3'l of the primary indicator is loca at 2|! to the side ofinstead of above the chart,

.and the arm 44' extends horizontally with'the marker moving in agenerally vertical arc over the upper middle portion of the circularchart. In this form the arm it is preferably a thin Walled stainlesssteel tube as shown Figures 18 to zfi'inclusive.

Under some conditions of operation, when. the chart paper is in closecontact with the chart plate at the markenthere is considerable tendencyof the marker to rebound with con- -siderable gain in amplitude ofmovement, ac-

companiedby some irregularity of vibration. Steps are preferably takento damp this exccssive vibration.

One very eifective corrective is by relieving or recessing the chartplate under the marker, or by cutting a slot ZIBthrough the chart platealong the range of movement of the marker,

By eliminating the support directly behind the paper along the path ofthe marker contact, thepaper apparently is permitted toabsorb the smallincrements of impact energy of vibration, which, if returned to themarker, result in up desirable interference with the original frequency.

A secondary advantage is obtained by slotting the metal chart plate usedin this form of re- The preferably rectangular Window symmetrical aboutthe vertical chart center line permits illumination from anelectric lamp225! to shine through the slot and the chart. The marker then serves asa hi hly visible indicator. Upper and lower reference lines 22l and 22sare suitably provided, preferably in red.

To further reduce undesirably high implitude of vibration, the impressedfrequency may to advantage in some cases be deliberately adjusted to aValue slightly oi? resonance, or (which proalso of avoiding blotting ortendency to pile up or splatter ink on the paper.

Figures 27 and 28 illustrate this condition. Figure 27 the pen (inkdischarge tube) B6, and the'ink stream 225 is of course tinuous to thepaper. is aththe opposite endof its vibration cycle,

, remotefrom the paper, but itonlymovcs away a short distance, of theorder of 0.805inch maximum, and so not break the ink column .Thus theink column is con- -14 tinuousandthemarkerline is continuous Withoutsplattering.

There is of course. some spring-back, of, the paper under theseconditions, ,and this permits an amplitude slightly, greater than the.distance which the pen leaves the paper without breaking the ink stream.

ln view of our invention and disclosure, variations and modificationstomeet individual whim particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of ourinvention Without copying the process and apparatus shown, and rtherefore, claim all such insofar as they fall within the reasonablespirit and scope of c r claims.

vingj thus described our invention What we as-new and desire to secureby Letters Patent is:

1. In a-recorder, marker arm adapted to rotate aboutan axis in responseto a quantity being-recorded, a marker toward theopposite and, of thearm'froin the axis and adapted to cooperate with a chart, a magneticallysusceptible armature on the marker arm at the axis, an electromagnetacting directly on the armature along the axis and thereby vibrating themarker arm at the axis and alternating cur rentmeans for energizing theelectromagnet to vibrate the marker in contact with the chart.

2. in arecorder, a marker arm movingabout in response to a quantitybeing measured, ha m" an axially resilient portion and tuned.

l respect to a particular frequency, a marksupported from the resilientportion of the any remote from the axis and adapted to cooperate With achart, amagnetically susceptible armatureon the marker ,arm at the axis,an electromagnet acting directly on the armature the axis and therebyvibrating the marker the axis and alternating current meanssubstantially the frequency for which the marker arm is tuned forenergizing the electromagnet to vibrate the marker in contact with thechart.

In arecorder, a marker arm moving about an axisin response to a quantitybeing measured. having an axially resilient portion and tuned withrespect to a particular frequency, a marker supported from the resilientportion of the arm remote from-the axis and adapted to cooperate achart, a magnetically susceptible armatureon the marker arm at the axis,an electronragnet acting directly on the armature along the axis andthereby vibrating the marker arm theaxis and alternating current meansslightoff with respect to the frequency for which the-marker arm istuned for energizing the electromagnet to vibrate the marker in contactwith the chart and damp the marker.

4. Ina recorder, a marker arm moving about an axis in response to aquantity being measured,

having an axially resilient portion and tuned "with respect toaparticular frequency, a'marker supported from the resilient portion ofthe arm remote-::fr0m the axis and adapted tocooperate with a .chart;a'niagnetica-lly susceptible armature-on the marker arm at the axis, anelectro- 1 magnet acting directly on the armature along the axis andthereby vibrating the marker arm at the axis and alternating currentmeans-slightly off with respect to the frequency for which the markerarm is tuned for energizing the electromagnet tovibrate the marker incontact with the chart and-by the offresonance character. limiting themarker to an amplitude not exceeding 0.005 inch away from the chart;

5. In a recorder, a marker arm moving about an axis in response to aquantity being measured, having a resilient portion and tuned withrespect to a particular frequency, a marker supported from the resilientportion or the arm remote from the axis and adapted to cooperate with achart, a chart support to the chart having an opening at the point atwhich the marker is located, leaving the chart unsupported where itcontacts the marker, a magnetically susceptible armature on the markerarm at the an elect-romagnet acting directly on the armature along theaxis and thereby vibrating the marker arm at the axis and alternatingcurrent means at substantially the frequency for which the marker arm istuned for energizing the electromagnet to vibrate the marker in contactwith the chart.

6. In a recorder, a marker arm moving about an axis in response to aquantity being measured, having a resilient portion and tuned withrespect to a particular frequency, a marker supported from the resilientportion of the arm remote from the axis and adapted to cooperate with achart, a chart Support for the chart having an opening at the point atWhich the marker is located, leaving the chart unsupported where itcontacts the marker, a magnetically susceptible armature on the markerarm at the axis, an electromagnet actin directly on the armature alongthe axis, and thereby vibrating the marker arm at the axis andalternating current means slightly off with respect to the frequency forwhich the marker arm is tuned for energizing the electromagnet tovibrate the marker in contact with the chart and damp the marker.

'7. In a recorder, a marker arm moving about an axis in response to aquantity being measured, having a resilient portion and tuned withrespect to a particular frequency, a marker supported from the resilientportion of the arm remote from the axis and adapted to cooperate with achart, a chart support for the chart having an opening at the point atwhich the marker is located, leaving the chart unsupported where itcontacts the marker, a magnetically susceptible armature on the markerarm at the axis, an electromagnet acting directly on the armature alongthe axis and thereby vibrating the marker arm at the axis andalternating current means slightly off with respect to the frequency forwhich the marker arm is tuned for energizing the electromagnet tovibrate the marker in contact with the chart and by the oil? resonancecharacter limiting the marker to an amplitude not exceeding 0.005 inchaway from the chart.

8. In a recorder, a primary indicator shaft turning in response to aquantity to be indicated, a marker arm on the shaft having a reversebend at the axis, a marker on the arm towards the end remote from theshaft and adapted to contact a chart, a magnetically susceptiblearmature on the arm at the side of the reverse bend remote from theshaft and at the axis, the reverse bend being axially resilient, anelectromagnet inside the reverse bend acting directly on the armaturealong the axis and thereby vibrating the marker arm at the axis andalternating current means for energizing the electromagnet to vibratethe marker in contact with the chart.

In a recorder, a primary indicator shaft turning in response tovariation in a quantity being measured, a marker arm on the shaft havingan axially resilient reverse bend and including a iii resilient markersupport on the side of the reverse bend remote from the shaft and at aposition re mote from the axis, the marker arm being tuned with respectto a particular frequency, a marker supported from the resilient markersupport and adapted to cooperate with a chart, a magnetical lysusceptible armature on the marker arm in line with the shaft axis onthe side of the reverse bend remote from the shaft, an electromagnetacting directly on the armature at the axis from inside the reverse bendand thereby vibrating the marker arm at the axis, and alternatingcurrent means at substantially the frequency for which the marker arm istuned energizing the electromagnet to vibrate the marker in contact withthe chart.

10. In a recorder, marl-lei arm adapted to ro tat-e about an axis inresponse to a quantity being recorded, a marker towards the opposite endof the arm from the axis including an ink pen adapted to cooperate withchart, a magnetically susceptible armature on the marker arm at theaxis, an elec romagnet acting directly on the armature along the axisand thereby vibrating the marker arm at the axis and alternating currentmeans for energizing the electromagnet to vibrate the marker in contactwith the chart, the amplitude of vibration under the particularalternating current means being so small at the pen that the inl: streamremains continuous to the chart throughout the vibration.

11. In a recorder, a marker arm adapted to rotate about an axis inresponse to a quantity being recorded, the marker arm having a resilientconnection at the axis, a resilient V-clip on the op posite end of thearm, a marker on the resilient V-clip adapted to cooperate with a chart,a magnetically susceptible armature on the marker arm at the axis, anelectromagnet acting directly on the armature along the axis and therebyvibrating the marker arm at the axis, and alternating current means forenergizing the electromagnet to vibrate the mark r in contact with thechart, the V-clip when holding the marker having a natural frequencywhich is resonant with the alternating current frequency.

12. In a recorder, a primary indicator shaft turning in response to aquantity to be indicated, a marker arm on the shaft having a reversebend at the axis, the reverse bend being axially re silient, a marker onthe arm towards the end rc-- mote from the shaft and adapted to contacta chart, a magnetically susceptible armature on the arm at the side ofthe reverse bend remote from the shaft and at the axis, anelect-romagnet out side the reverse bend acting directly on the armaturealong the axis and thereby vibrating the marker arm at the axis,alternating current means for energizing the electromagnet to vibratethe marker in contact with the chart.

13. In a recorder, a marker rm adapted to rotate about an axis inresponse to a quantity being recorded, having a resilient portion andtuned with respect to a particular frequency, a marker supported fromthe resilient portion of the arm remote from the axis and adapted tocooperate with a chart, a magnetically susceptible armature on themarker at the an electromagnet acting directly on the armature along theand thereby vibrating the marker arm at the axis and alternating currentmeans for energizing the electromagnet to vibrate the marker in contactwith the chart.

14. In a recorder, a marker arm adapted to rotate about an axis inresponse to a quantity being recorded, a marker toward the opposite endof the arm from the axis and adapted to cooperate with a chart, a chartmounting for the chart rotatable about an axis transverse to-the markerarm axis, a chart support having a curved portion conforming to thecurved path of the marker, a magnetically susceptible armature on themarker arm at the axis, an electromagnet acting directly on the armaturealong the axis and thereby vibrating the marker arm at the axis andalternating current means for energizing the electromagnet to vibratethe marker in contact with the chart.

15. In a recorder, a chart mounting rotatably about the axis, a flatchart support extending in a plane transverse to the axis of the chartmounting, a marker arm adapted to rotate about an axis above and to oneside 01' the chart support and in response to a quantity bein recorded,a marker toward the opposite end of the arm remote from the marker armaxis and adapted to cooperate with a chart on the chart mounting, amagnetically susceptible armature on the marker arm at the marker armaxis, an electromagnet acting directly on the armature along the markerarm axis and thereby vibrating the marker arm at the marker arm axis,and alternating current means for energizing the electromagnet tovibrate the marker in contact with the chart.

DAVID ROBERT YARNALL. JAMES W. WILLIAMS, 3m).

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 533,270 Bristol Jan. 29, 1895626,848 Wills June 13, 1899 654,103 Schrottke July 17, 1900 372,193Orling Nov. 26, 1997 974,190 Robinson 1 Nov. 1, 1910 1,038,297 Clawson 1Sept. 10, 1912 1,131,892 Alger Mar. 16, 1915 1,513,889 Brown Nov. 4,1924 1,521,007 Chubb Dec. 30, 1924 1,717,094 Clokey -1 June 11, 19291,760,947 Healey June 3, 1930 2,125,983 Bettison et a1 Aug. 9, 19382,158,468 McCleary May 16, 1939 2,269,240 Anderson Jan. 6, 19422,403,472 Anderson July 9, 1946 2,447,191 Lingel Aug. 17, 1948

